[Mark Yacavone]

Mike, in my opinion, you can't spend too much time on a Buick oiling system.
When you analyze it, you'll see that that rear main bearing's oil is, effectively about 3 ft away from the pick up..
Drill out the pick up passage in the block. "Port match" all the transitions in the oil passages. Use the T/A parts to blueprint the oil pump clearances, use the adjustable PR stop . Baffle the pan in the rear etc,etc,etc...
When you get all done, don't be alarmed if you only have 10-15 psi at idle after a run!
Rev it up a little and watch the gauge. If you have at least 10 psi per 1000 RPM's, you'll be fine.